Risk of clinical mastitis in dairy herds with a high proportion of low individual milk somatic-cell counts

The relationships between the herd-somatic-cell count (SCC) pattern on a test day and the incidence of clinical mastitis in the subsequent period were studied by collecting health data and monthly records from 2 years (1995-1997) from 121 farms located in the west of France. A total of 980 herd-periods (from one test day to the following one) were analyzed. The outcome variable was the incidence density of clinical mastitis (ICM) within the herd-period. The herd-SCC pattern on a test day was described by cross-combining the proportions of cows with low SCC (<50,000 cells/ml) or with high SCC (>250,000 cells/ml). The relationship between herd-SCC pattern and subsequent ICM was assessed using a generalized linear mixed model. A sensitivity analysis evaluated the effect of different proportions of cows with low SCC on significance and magnitude of the relationship. Risk of clinical mastitis was expressed as a risk ratio (RR) in comparison to a moderate herd-SCC level (with low proportions of cows with low or high SCC).Median ICM was 0.38 cases per 365 cow-days at risk (first and third quartiles: 0 and 0.88). In the situations where few cows (<15%) had SCC>250,000 cells/ml, ICM was higher (RR>1.31) when the proportion of cows with low SCC exceeded 50% than in the reference situation. Risk ratios increased as the proportion of cows with low SCC increased from 40 to 60%. In the situations where the proportion of cows with SCC>250,000 cells/ml exceeded 15%, ICM was higher compared to the reference situation (whatever the proportion of low SCC). Risk ratios were also higher when the proportion of cows with low SCC were >40-60%, compared to the pattern with the proportion of cows with low SCC below 40%. Herd situations with a high proportion of cows with low SCC appeared to be at increased risk of clinical mastitis.     

Effect of oral administration of colostrum on inflammation in the udders of dairy cows suffering from mastitis

The present study was undertaken to examine whether oral administration of colostrum to mastitic cows reduced inflammation in the udder. Fifty milliliters of a colostrum whey product was administered orally daily for 3 days to cows suffering from mastitis. Milk was collected on day 0 and 7 of colostrum administration. For Experiment 1, milk from 11 udder quarters with high somatic cell counts (SCC) in four cows was used. SCC in milk decreased significantly after colostrum administration, whereas colostrum administration increased sodium and IgA concentrations significantly compared with those before administration. In Experiment 2, cows with clinical mastitis were divided into two groups, with and without colostrum administration, whereas all cows with subclinical mastitis were administered colostrum. Antibiotics were infused into the mammary gland from the first day of colostrum administration for 2–4 days. There was no significant decrease in SCC after colostrum administration in any group. However, udder firmness in both clinical mastitis groups was reduced after administration regardless of colostrum administration. IgA concentration in both clinical mastitis groups was significantly increased after colostrum administration compared to that before administration, although there was no significant difference between them. These results suggest the possibility that oral administration of colostrum attenuates inflammation of the mammary gland. Further studies are required to examine the effect of colostrum more precisely using cows with subclinical and chronic mastitis and longer duration of colostrum administration.     

Dynamics of lingual antimicrobial peptide,lactoferrin concentrations and lactoperoxidase activity in the milk of cows treated for clinical mastitis

The aim of the present study was to examine changes in innate immune factors in the milk of mastitic dairy cows treated with antibiotics. Cows in the antibiotics group (n = 13) were infused into the mammary gland with cefazolin on the sixth day after mastitis was diagnosed (the day of the mastitis diagnosis = day ?6). The control group (n = 12) was not treated. Milk samples were collected once every 2 days from days ?6 to 12 and somatic cell count (SCC), lingual antimicrobial peptide (LAP), and lactoferrin (LF) concentrations and lactoperoxidase (LPO) activity were measured. SCC and LF concentrations in the antibiotics group markedly decreased after the antibiotic treatment. When cows in the antibiotics group were divided according to SCC on day 0, LAP concentrations and LPO activity in cows with a lower SCC on day 0 (<5 × 10⁶ cell/mL) were significantly higher and lower than those in cows with a higher SCC, respectively. These results suggest that LF concentration decreased with decrease in SCC after treatment and that LAP concentration and LPO activity differed depending on the severity of mastitis. This is the first report to reveal the dynamics of innate immune factor in milk of cows treated for clinical mastitis.     

Prevalence of clinical mastitis in 38 Waikato dairy herds in early lactation

AIM: To determine the prevalence of clinical mastitis in spring-calving dairy herds in the Waikato Region of New Zealand and to identify factors associated with variation in the prevalence of clinical mastitis between herds. METHOD: A total of 799 quarters from 595 dairy cows from 38 dairy herds were diagnosed by herd owners as having clinical mastitis between 8 July and 21 August 1997. Quarters diagnosed with clinical mastitis were sampled for bacterial culture and somatic cell count, and the presence of clots in the milk and the presence of udder oedema were assessed by a technician or veterinarian. RESULTS: Clinical mastitis was diagnosed in an average (+/-s.e.m.) of 9.9% (+/-0.8%, range 0.9-21.4%) of calved cows within the herds. Bacteria were not cultured from an average of 12.4 % (+/- 2.0%, range 0.0-45.5%) of cows and 22.3% (+/- 2.4%, range 0.0-54.0%) of quarters diagnosed as having clinical mastitis. There were significant differences between herds in the proportion of cows diagnosed with mastitis and in the proportion of clinical mastitis cases from which bacteria were not cultured. A decreased prevalence of clinical mastitis (p<0.001) was associated with an increased percentage of the herd treated with dry cow antibiotics. An increased prevalence of clinical mastitis (p<0.0001) was associated with both an increased percentage of cows treated in the previous season with lactating cow antibiotics and an increased percentage of heifers in the herd. Herds that were fed supplements before or during lactation had a higher prevalence of clinical mastitis than herds that were not fed supplements (p<0.001). An increased proportion of quarters diagnosed with clinical mastitis that did not culture bacteria was associated with an increased prevalence of clinical mastitis (p<0.001). The proportion of quarters that the technician or veterinarian found with evidence of clinical mastitis (i.e. a somatic cell count >500,000 cells/ml and the presence of either clots or udder oedema) within a herd was inversely related to the proportion of quarters within a herd from which no bacteria were isolated. CONCLUSION: There was a large variation in the prevalence of clinical mastitis and in the proportion of clinical quarters from which no bacteria were grown between herds. Management factors such as the use of dry cow therapy, feeding regimes and heifer replacement rates all affected the prevalence of clinical mastitis. Herd owners appear to differ in the sensitivity and specificity of their diagnosis of clinical mastitis, with bacteria not isolated from up to 50% of quarters diagnosed with clinical mastitis in some herds. Improvements in the specificity of herd owner diagnosis of clinical mastitis may reduce the use of antibiotics for mastitis during lactation and hence may reduce the risk of antibiotic contamination of milk supplied for human consumption.     

Reliability in somatic cell count measurement of clinical mastitis milk using DeLaval cell counter

Somatic cell counts (SCC) measurements are typically performed using quantitative methods, such as the Breed method (Breed) and the Fossomatic method (FSCC). The DeLaval cell counter (DCC) developed recently is a quantitative somatic cell counter with a low initial cost and superior portability. However, since the DCC was specifically developed for measuring SCC of ≤ 4 × 10⁶ cells/mL milk from bulk tanks or individual cows, its reliability for estimating SCC that exceed this concentration has not yet been clarified. This study therefore examined whether it is possible to accurately measure SCC by diluting milk samples with initial SCC of 4 × 10⁶ cells/mL, as seen in clinical mastitis milk. We collected milk samples from 99 quarters of 99 Holstein cows with clinical mastitis. These milk samples were diluted 10‐fold with saline and thoroughly mixed before performing SCC measurement with the DCC. The correlation coefficients of SCC measured by the FSCC, Breed and DCC methods indicated strong correlations between each pair of methods. The findings showed that DCC can be used to identify bovine clinical mastitis milk and is useful as a quantitative SCC measurement device on farm sites.     

The use of Markov chain Monte Carlo for analysis of correlated binary data: patterns of somatic cells in milk and the risk of clinical mastitis in dairy cows

Two analytical approaches were used to investigate the relationship between somatic cell concentrations in monthly quarter milk samples and subsequent, naturally occurring clinical mastitis in three dairy herds. Firstly, cows with clinical mastitis were selected and a conventional matched analysis was used to compare affected and unaffected quarters of the same cow. The second analysis included all cows, and in order to overcome potential bias associated with the correlation structure, a hierarchical Bayesian generalised linear mixed model was specified. A Markov chain Monte Carlo (MCMC) approach, that is Gibbs sampling, was used to estimate parameters.

The results of both the matched analysis and the hierarchical modelling suggested that quarters with a somatic cell count (SCC) in the range 41,000–100,000 cells/ml had a lower risk of clinical mastitis during the next month than quarters <41,000 cell/ml. Quarters with an SCC >200,000 cells/ml were at the greatest risk of clinical mastitis in the next month. There was a reduced risk of clinical mastitis between 1 and 2 months later in quarters with an SCC of 81,000–150,000 cells/ml compared with quarters below this level. The hierarchical modelling analysis identified a further reduced risk of clinical mastitis between 2 and 3 months later in quarters with an SCC 61,000–150,000 cells/ml, compared to other quarters.

We conclude that low concentrations of somatic cells in milk are associated with increased risk of clinical mastitis, and that high concentrations are indicative of pre-existing immunological mobilisation against infection. The variation in risk between quarters of affected cows suggests that local quarter immunological events, rather than solely whole cow factors, have an important influence on the risk of clinical mastitis. MCMC proved a useful tool for estimating parameters in a hierarchical Bernoulli model. Model construction and an approach to assessing goodness of model fit are described.     

Impact of Mastitis Control Measures on Milk Production and Mastitis Indicators in Smallholder Dairy Farms in Kiambu District,Kenya

Bovine mastitis and mastitis control were investigated on smallholder farms in central Kenya. After an initial observational study, a clinical trial to assess the impact of three different mastitis control strategies – (1) improved udder hygiene, (2) treatment of subclinical cases, and (3) a combination of these – was conducted on 100 randomly selected farms with 332 lactating cows. Before the implementation of control measures, the milk yield was low (mean 6.5 kg/day; median 6 kg/day) and somatic cell counts (SCC) were high, with 80% and 43% of cows having milk with SCC greater than 250×10³ cells/ml and 600×10³ cells/ml, respectively. Infectious pathogens were also commonly isolated, with 63% of cows being positive for pathogenic bacteria. Neither intervention strategy alone had any effect on mastitis indicators or milk yield. In combination, the measures had some impact, lowering the prevalence of contagious pathogens by 18%, but this was not reflected in a significantly increased milk yield, lowered SCC or reduced incidence of clinical mastitis.     

Withdrawal periods and tissue tolerance after intramammary antibiotic treatment of dairy goats with clinical mastitis

The aim of this study was to determine withdrawal periods (WP) and tissue irritation after administration of three intramammary antibiotics [Curaclox LC (Norbrook (ARK AH)], Spectrazol Milking Cow (Schering-Plough AH) and Rilexine 200 LC [Logos Agvet (Virbac)] in goats with clinical mastitis. Withdrawal periods in goats with clinical mastitis treated with Curaclox LC, were not significantly different from those recommended for use in cows (72 h) with (67 h) or without (48 h) the 24 h mandatory safety margin while Spectrazol caused a significantly longer withdrawal period (122 h) than that recommended for use in cattle with (60 h) and without (36 h) the 24h safety margin. The withdrawal period of clinical mastitis cases treated with Rilexine 200 LC was 48 h compared to the 96 h recommended for use in cows. A linear model of regression with factors influencing the WP in goats with clinical mastitis was as follows: WP = 30.21 + 4.692 (sampling time) + 22.11 (udder pathology) - 13.6 (floccules) - 0.00649 (milk yield). Somatic Cell Counts (SCC) of milk from udder halves with clinical mastitis ranged from 7,053 x 10(3) to 7,948 x 10(3) cells per ml without isolations of bacteria and between 6,476 x 10(3) and 8,479 x 10(3) cells per ml with isolations of bacteria. Most of the variation in SCC could not be explained and the California Milk Cell Test (CMCT) and SCC on their own were not reliable methods for mastitis diagnosis. However, CMCT and SCC were indicators of udder irritation. In goats without clinical mastitis, Spectrazol Milking Cow caused the least tissue irritation followed by Rilexine 200 LC and Curaclox LC. For goats with clinical mastitis, Rilexine 200 LC caused the least irritation, followed by Curaclox LC while Spectrazol Milking Cow caused the most irritation.     

Milk flow and udder health in cows after treatment of covered teat injuries via theloresectoscopy: 52 cases (2000-2002)

OBJECTIVE: To determine milk flow, somatic cell counts (SCCs), and the incidence of clinical mastitis in cows that had undergone theloresectoscopy for treatment of teat stenosis caused by mucosal detachment in the region of the streak canal or Fürstenberg's rosette. DESIGN: Retrospective study. ANIMALS: 52 cows with teat stenosis that were treated via theloresectoscopy. PROCEDURE: Medical records of eligible cows were reviewed. Additional data regarding milking ease, SCC, development of clinical mastitis of the affected gland, and whether the cow remained in the herd were collected via owner-completed questionnaires. RESULTS: 49 of 52 questionnaires were completed. At referral, teat sinusitis was diagnosed in 29 of 52 cows. Milk flow was normal in 38 of 41 treated teats at discharge and in 24 of 40 during the next lactation. Thirteen of 49 cows were culled during the next lactation because of abnormal udder health. High SCC and teat sinusitis at referral and development of clinical mastitis during the 10-day period after surgery resulted in high SCCs in the remainder of the current lactation. The incidence of clinical mastitis during the remainder of the current and during the next lactation was higher in cows that had teat sinusitis at the time of surgery, compared with those that did not. CONCLUSIONS AND CLINICAL RELEVANCE: Teat stenoses resulting from mucosal lesions in the region of the streak canal or Fürstenberg's rosette may be successfully treated via theloresectoscopy. Inflammation of the teat sinus and gland at the time of surgery may adversely affect udder health.     

Efficacy of blanket treatment of cows and heifers with an internal teat sealant in reducing the risk of mastitis in dairy cattle calving on pasture

AIM: To evaluate the benefit of blanket treatment of all milking cows at drying-off and all replacement heifers one month prior to the planned start of mating with an internal teat sealant on the incidence of mastitis, and somatic cell counts (SCC), postpartum in a 650-cow herd with a mastitis incidence in early lactation of 15% in cows and 26% in heifers. METHODS: Prior to drying-off, lactating cattle were divided on the basis of SCC and mastitis history. Cattle with records of individual SCC >150,000 cells/ml or mastitis in the previous lactation were treated with a cloxacillin-based dry-cow therapy (DCT), while the remaining cattle received no antibiotics. Cattle in each of the two groups were then randomly assigned to receive either an internal teat sealant or no further treatment. Additionally, one month prior to the planned start of calving the rising 2-year-old heifers were also randomly assigned to receive either an internal teat sealant or no treatment. All clinical mastitis cases were recorded for the first 10 weeks after the start of calving, while SCC were measured on three occasions during the subsequent lactation. RESULTS: Data were available from 466 cows and 206 heifers; treatment with the internal teat sealant significantly reduced the incidence of mastitis in both groups. For cows, the reduced risk of mastitis due to treatment with the teat sealant was not significantly different between cows, which, based on their mastitis history, required dry-cow antibiotics and those which did not. There was no effect of teat sealant on the mean SCC of any group at any time-point. CONCLUSIONS: On this farm, treatment of all cows and heifers prior to parturition with an internal teat sealant significantly reduced the risk of clinical mastitis. The benefits of an internal teat sealant were the same when used in combination with antibiotics in cows with a history of mastitis as when used alone in cows with no such history. CLINICAL RELEVANCE: These data support the proposition that blanket treatment with an internal teat sealant of all cows due to enter the milking herd can be a useful method of mastitis control. They also suggest that combined therapy with dry-cow antibiotics and internal teat sealants can be beneficial under New Zealand conditions. More detailed research on more farms in more areas of New Zealand is required to confirm these suggestions.     

复方阿莫西林乳房注入剂对临床型奶牛乳房炎的治疗效果

为评价复方阿莫西林乳房注入剂对泌乳期奶牛临床型乳房炎的治疗效果,在甘肃某两个牛场选择70头自然发生的临床型乳房炎奶牛进行临床试验.将患病奶牛随机分为试验组(n=36头)和对照组(n=34头).试验用药和对照用药分别为郑州百瑞动物药业有限公司和齐鲁动物保健品有限公司提供的复方阿莫西林乳房注入剂.每个感染乳区注入3 g药物...     

Therapeutic effects of systemic or intramammary antimicrobial treatment of bovine subclinical mastitis during lactation

The short- and long-term treatment efficacy of administrating penicillin for bovine subclinical mastitis during lactation when using intramuscular (IM; 9.5 mg [15,000 IU]/kg bodyweight of benzyl penicillin potassium) injections twice daily for 5 days, or intramammary (IMM; 0.3g [300,000 IU] penethamate hydroiodide) administration once daily for 5 days was compared with a control group receiving no treatment. One hundred and twenty-six cows met the inclusion criteria, which were lack of clinical symptoms, no recent treatment with antimicrobials, and findings of penicillin-sensitive Staphylococcus aureus, Streptococcus dysgalactiae, or Streptococcus uberis in combination with an inflammatory reaction. At follow-up 42-58 days after treatment, the proportion of cows negative for the original infection was significantly higher in IM and IMM groups compared to controls, but the difference between antimicrobial treatment groups was not significant. The udder quarter milk somatic cell count (SCC) was significantly lower at follow-up in IM and IMM groups than in controls, but milk production did not differ between treatments. The culling rate during the 10-month period following treatment was significantly higher in the group treated with IMM penicillin than in the other two groups, but the risk of new mastitis treatments within 10 months did not differ between the three groups. The cure rate was significantly affected by lactation number (lower in older cows), breed (lower in the Swedish Holstein breed), pathogen (lower for S. aureus), and pre-treatment SCC (higher for above average SCC). In conclusion, beneficial long-term effects of antimicrobial treatment during lactation of subclinical mastitis caused by S. aureus, Str. dysgalactiae or Str. uberis were not found in the present study.     

An epidemiological and genetic study on registered diseases in Finnish Ayrshire cattle. IV. Clinical mastitis

The epidemiology and genetic variability of clinical mastitis were examined. The data consisted of 70,775 Finnish Ayrshire cows. All cows were from milk recorded herds and calved during 1983. Each cow was under observation from the date of calving for 305 days. Only clinical mastitis diagnosed and treated by a veterinarian during the farm visits were taken into account. The lactation incidence rate of clinical mastitis (LIR) was 5.4 %. The cows calving in April-May had the highest LIR, but the seasonal variation was relatively small. The LIR increased with parity from the first to sixth parity. The cows treated for parturient paresis, infertility or ketosis had a higher risk of clinical mastitis than cows not treated for these diseases. The LIR was higher in herds with a high milk production level. The highest odds ratio estimated from parameters of the logit model was 14.8. The heritability estimates for clinical mastitis on the binomial scale were 3.2 % in parity 1, 1.6 % in parity 2, 0.6 % in parity 3 and 4, and 0.8 % in all parities (corresponding to 19.7 %, 8.3 %, 2.6 % and 3.8 % on the normal scale). These estimates indicate sufficient assurance for progeny testing of bulls and some possibilities of genetic selection against clinical mastitis. Genetic correlations between clinical mastitis and 305-days milk yield were 0.39 in parity 1, 0.51 in parity 2, 0.18 in parity 3–4 and 0.58 in all parities. This means that the best sires for milk yield had daughters with a higher LIR for clinical mastitis than the other sires.     

Dynamics of Staphylococcus aureus infections during vaccination with an autogenous bacterin in dairy cattle

The effect of an autogenous vaccine against Staphylococcus aureus on S. aureus prevalence and mastitis, as well as on somatic cell count (SCC), was studied in a dairy herd with a high prevalence of S. aureus. The vaccination group (n = 35; 22 cows and 13 heifers) and the control group (n = 36; 23 cows and 13 heifers) received the vaccine or a placebo, respectively, according to the following protocol: all animals: basic immunization (twice, 3 weeks apart); cows: booster dose at the time of drying off, 5 and 2 weeks before calculated calving date; heifers: booster dose 2 and 5 weeks before calculated calving date. The vaccine or the placebo was administered subcutaneously in the area of the supramammary lymph nodes. Quarter milk samples were collected monthly and subjected to SCC and bacteriological evaluation. At this time, the animals were also checked for signs of clinical mastitis. Non-clinical S. aureus mastitis diagnoses were based on udder quarter SCC and a positive S. aureus culture. In order to compare the SCC in individual whole milk samples, records from the monthly milk quality testing were evaluated. Cow and udder quarter prevalence of S. aureus intramammary infections calculated for the experimental animals and quarters, respectively, did not differ between groups. However, during the lactation period following the boostcr dose, the prevalence of S. aureus increased in both groups (P < 0.05). The cumulative incidence of various mastitis diagnoses (clinical, subclinical, latent infection) due to S. aureus on an animal basis did not differ between groups. On an udder quarter basis, the cumulative incidence of subclinical mastitis was higher in vaccinated animals than in control animals (33.8 versus 26.0%; P < 0.05). This was mainly due to a higher cumulative incidence of subclinical mastitis in vaccinated than control heifers. The SCC in composite milk samples did not differ between groups, but increased as lactation progressed. The herd prevalence of S. aureus differed considerably throughout the study period, but declined consistently to below 10% at the end of the study period. Recent herd checks revealed a prevalence of S aureus infections of < 5%. It is concluded that the autogenous bacterin tested in this study did not have the desired effect on the prevalence of S. aureus infections and mastitis or SCC. The decline in S. aureus prevalence was very probably due to other factors than specific immunization against S. aureus.     

Relation of milk production loss to milk somatic cell count.

Milk production loss was studied in relation to increased somatic cell count (SCC). Available data were weekly test-day milk yields and SCC (in 1,000 cells/ml), and mastitis incidences. In total, 18,131 records from 274 cows were used. Production loss was determined for test-day kg milk, kg protein, and kg energy-corrected milk. Least-squares analysis of variance was used to estimate the direct effect of Log10(SCC) on production. The recorded measures of production were first corrected for fixed effects, with adjustment factors estimated from a healthy data-set. The average daily milk yield was 19.7 kg/day in first lactation and 22.0 in later lactations. The geometric mean of SCC was 63.1 in first lactation and 107.2 in later lactations. The incidence of clinical mastitis treated by a veterinarian was 19.8% of the lactations-at-risk. Linear relationships were found between the production parameters and Log10(SCC). Quadratic and cubic effects were evaluated, but were found to contribute little to the overall fit of the models. The individual milk yield loss was 1.29 kg/day for each unit increase in Log10(SCC) for cows in first lactation. Milk yield decreased by 2.04 kg/day per unit Log10(SCC) for older cows. Corresponding values for protein yield were 0.042 and 0.067 kg/day for first and later lactations, respectively.     

Comparative efficacy of three dry-cow antibiotic formulations in spring-calving New Zealand dairy cows

AIM: To evaluate the efficacy of a dry-cow antibiotic preparation containing cloxacillin plus ampicillin in a formulation that gives a 10-week duration of action, in comparison to products containing cephalonium (10-week action) or cloxacillin alone (7-week action). METHODS: A total of 493 cows were selected from 6 spring-calving dairy herds in the Manawatu region of New Zealand, according to the criteria of the SAMM plan, to receive intramammary antibiotic therapy at the end of lactation (drying off). Cows were randomly allocated to receive 1 of the 3 dry-cow antibiotic products under investigation. Cows were examined twice during the dry period and twice daily during the first 10 days of their subsequent lactation for the presence of mastitis. Milk samples were collected from individual quarters at the time of drying off and at 7 and 28-35 days after calving, for determination of milk somatic cell counts (SCC). Bacteriology was carried out on milk samples taken from cows that developed mastitis during the first 10 days after calving. RESULTS: No cows developed mastitis during the dry period. Sixteen cows developed clinical mastitis within 10 days of calving; there was no difference in incidence between treatments. Streptococcus uberis was the most commonly isolated organism. Mean SCC on Day 7 were lower (p = 0.019) in cephalonium-treated quarters (189.9+/-28.4 x 10(3) cells/ml) than in cloxacillin-treated quarters (388.7+/-71.2 x 10(3) cells/ml); values in quarters receiving cloxacillin plus ampicillin were intermediate (252.0+/-47.0 x 10(3) cells/ml). SCC were similar between treatment groups on Day 28-35. CONCLUSIONS: The use of a combination of cloxacillin plus ampicillin was effective for the prevention of mastitis during the dry and peri-calving-periods in pastured dairy cattle.     

Intramammary application of ozone therapy to acute clinical mastitis in dairy cows

The infusion of ozone into the inflamed quarter of cows with clinical mastitis was performed and the efficacy of ozone therapy was evaluated. Ozone was infused into the inflamed quarter via a teat canal using ozone gas generating equipment. Nineteen Holstein cows with acute clinical mastitis were divided into two groups: 15 cows treated with ozone therapy, and 4 cows treated with antibiotic therapy. Systemic and local clinical signs, California Mastitis Test scores, the mastitis causing pathogens, electronic conductivity of milk, and somatic cell counts in milk from ozone- and antibiotic-treated quarters, were compared between the groups. Sixty percent (9/15) of cows with acute clinical mastitis treated with ozone therapy, did not require any antibiotics for recovery. This newly developed ozone therapy method was proven to be effective, safe, and cost effective, and carries no risk of drug residues in milk.     

新疆石河子地区某规模化奶牛场乳房炎患病率调查

对新疆石河子地区某规模化奶牛场的712 头澳系荷斯坦泌乳牛进行乳房炎患病率调查。调查结果显示,40 头奶牛患临床型乳房炎,患病率为5.62%。从剩余的未表现出临床乳房炎症状的672 头奶牛中随机选出180 头奶牛,共682 个乳区（720 个乳区中有38 个瞎乳头）,分别进行兰州乳房炎检测（LMT）和乳样体细胞数（SCC）检测。经LMT诊断发现,180 头奶牛中有56 头患隐性乳房炎,患病率为31.11%;经SCC检测发现,180 头奶牛中有60 头患隐性乳房炎,患病率为33.33%。数据分析发现：各乳区患乳房炎阳性率差异不显著（P>0.05）,说明各乳区阳性率之间没有必然规律;6岁以上奶牛的乳房炎患病率与2~3岁、4~5岁的患病率相比差异显著（P<0.05）,说明6岁及以上奶牛乳房炎的患病率要高于2~3岁、4~5岁奶牛;6胎及以上的奶牛乳房炎患病率与其他胎次之间差异极显著（P<0.01）,说明6胎及以上奶牛的乳房炎患病率要远高于1胎、2胎、3胎、4胎、5胎奶牛。     

Efficacy of intramuscular treatment of beef cows with oxytetracycline to reduce mastitis and to increase calf growth

Spring-calving multiparous Angus x Hereford cows were used to determine the efficacy of intramuscular treatment with oxytetracycline to reduce the incidence of mastitis-causing bacteria, decrease milk somatic cell counts (SCC), and increase calf growth. During 2 yr, milk samples were collected from each quarter from a total of 319 cows at 8 to 14 d after calving and at weaning, to determine the presence of bacteria and SCC. A California mastitis test (CMT) was performed on milk from each quarter of each cow at the initial sample collection. Cows with a CMT score of 1, 2, or 3 in at least one quarter, were randomly assigned to receive either an intramuscular injection of oxytetracycline (n = 63) or the control vehicle (n = 60), and cows with a CMT score of 0 or trace in all four quarters were not treated (n = 196). Calf weights were determined at birth, early lactation, and weaning. The number of somatic cells in milk and the percentage of quarters that were infected increased as CMT score increased (P < 0.01). The presence of mastitis-causing bacteria at calving increased (P < 0.05) the incidence of infection at weaning. The presence of mastitis-causing bacteria at weaning was associated with increased SCC for quarters and average SCC for cows (P < 0.01). Average SCC per cow at weaning increased (P < 0.05) as the number of infected quarters per cow increased. Treatment did not alter (P > 0.10) the percentage of cows or quarters infected with mastitis-causing bacteria or SCC of cows or quarters at weaning. Average SCC per cow was negatively correlated (P < 0.05) with calf weights at early lactation, but not with weaning weights of calves. Treatment did not influence (P > 0.10) calf weights at early lactation or at weaning. Cows with one or more dry quarters after calving had calves that weighed less at early lactation and weaning than cows with four functional quarters (P < 0.01). Intramuscular oxytetracycline treatment of beef cows that had CMT scores of 1 or greater after calving did not reduce intramammary infection rates or increase calf weights at weaning.